A variety of documents are displayed on a display device of a computer. A Web page accessed through the Internet is one of such documents. Incidentally, as types and contents of information submitted through the Internet have been enriched more in recent years, an amount of information per Web page has also been increased more. Consequently, there has occurred a situation where the Web page becomes too large to fit in a display screen of the display device. Such a situation is one occurring also in the case where the aged and persons having weak eyesight zoom the document for the purpose of reading characters displayed on the display device.
This situation where the document such as the Web page becomes too large to fit in the display screen causes a plurality of problems described below. First, there occurs a problem that a user is forced to perform a scroll operation. This scroll operation is usually performed by raising or lowering a scroll bar with a mouse, and therefore, becomes a cumbersome operation for a user. Particularly, for an aged person and a user who is not good at adjusting his/her body delicately, the scroll operation is one involving difficulty.
Moreover, since it becomes unable to view the whole page at a glance, such problems as below also occur particularly for the aged person: it becomes difficult to grasp the layout of the whole of the page (load on comprehension); it becomes difficult to find a target section from the whole of the page (load on attention); and it is necessary to remember a content of an upper part of the page when reading a lower part thereof (load on a shortterm memory). Today, when our society is aging rapidly, such problems as described above are serious.
As a method for solving the problems described above, a method for creating a digest of the document such as the Web page is conceivable, in which a display area of the document is fitted within an area designated by a reader. In this case, it is desirable if not only the display area is merely fitted to the designated area but also areas occupied by respective portions constituting the document can be allocated in accordance with significance thereof to effectively utilize the display area.
Heretofore, as this type of technology, there has been a method for creating a digest of the Web page, in which a layout of the Web page is automatically analyzed based on tags of an HTML (refer to Patent Document 1). In this method, the Web page is divided while tracing a tree structure, in which strength of each tag of the HTML is reflected on a hierarchy, from a root thereof to a leaf direction, and the page the digest of which is to be displayed is sorted. Then, contents to be displayed in the respective regions sorted in accordance with significance of the tags of the HTML are decided so as not to delete important information.
Moreover, as another conventional technology, there is a method for creating a digest of a Web page based on annotations (refer to Non-Patent Document 1). In this method, locations and significance of regions, which are obtained by external annotations, are utilized. Specifically, the locations of the regions on the digest are decided based on the regions designated by the annotations, and a plurality of regions designated to have high significance by the annotations are displayed while trying to maintain original area ratios thereof as much as possible.
Furthermore, as still another conventional technology, there is a method in which a layout of a plurality of articles are automatically decided (refer to Patent Document 2). In this method, articles are being divided into groups of the articles the numbers of which become smaller step by step with reference to significance of the articles, and display areas for the groups of articles to be displayed are being decided sequentially until all the numbers of articles belonging to the respective groups of articles become one.
[Patent Document 1] Gazette of Japanese Patent LaidOpen No. 2001-184344 (pp. 5-6, FIG. 13)
[Patent Document 2] Gazette of Japanese Patent LaidOpen No. Hei 9 (1997)-330314
[Non-Patent Document 1] Maeda and three others, “Digesting Technology for Web Page Based on Annotation,” Technical Research Report (Welfare Information Technology) of The Institute of Electronics, Information and Communication Engineers, 2001, vol. 101, No. 263, pp. 25-30
However, in the foregoing digest creation method using the tags of the HTML, the Web page is being divided in accordance with the tree structure in which the layout is reflected, and therefore, information cannot be shared among the regions that have already been branched, and the areas cannot be allocated to the regions optimal for the whole page.
In the foregoing digest creation method using the annotations, the areas are allocated to regions in consideration of the significance thereof for the whole page. However, in this conventional technology, all of the regions are displayed in order to ensure accesses to digested regions. Therefore, it cannot be said that the limited display area can be effectively utilized, and when the number of regions is large, it is not ensured that the digest fits in the display area required by the reader.
Also in the foregoing method in which the layout of the plurality of articles is decided, similarly to the above, the display areas of the articles are decided for the whole of the page in accordance with the significance of the articles. However, in this conventional technology, the articles are grouped and arranged in accordance with the significance thereof, and therefore, this technology cannot be applied to a document the layout of which is predetermined. In addition, in this technology, a relatively few number of articles are assumed, and all of the articles are to be displayed. Accordingly, it becomes impossible to ensure that the articles will be fitted in the area required by the reader when the number of articles becomes larger. Note that, when the total area is forcibly limited, only a small area insufficient for practical use will be allocated to an article the significance of which is low.
Hence, it is desirable to realize a system for creating a digest of a document, in which a document, such as a Web page, the layout of which is predetermined by a creator, is transformed to certainly guarantee that the transformed document will fit within a display area required by a reader, and areas are optimally allocated to divided regions so as to make the most of the display area. At this time, it is necessary to ensure accesses to information lost by creating the digest.
From this point of view, for example, in the foregoing digest creation method using the tags of the HTML, when a desired region is designated, the whole content of the region is displayed by detailed content displaying means, and such lost information can be acquired. However, accesses to regions that are not displayed on a digest screen at all cannot be ensured by this method.
Moreover, it is desirable to realize a system enabling such browsing as approaching a target portion, in which digests are created also on detail screens, and a range from which information is to be acquired is narrowed step by step while confirming the whole structure of a page. Furthermore, from a viewpoint of providing a more comfortable browsing environment, it is desirable to realize a system for changing displays of digests and detailed contents in response to an operation of a user.